Method and apparatus for media independent handover capability discovery

ABSTRACT

A first media independent handover function (MIHF) receives a media independent handover (MIH) capabilities discovery request from a second MIHF and generates a MIH capabilities discovery response message, including one or more parameters. Then the first MIHF then sends the MIH capabilities discovery response to the second MIHF. Based on the information contained in the MIH capabilities discovery response, the first MIHF may receive a handover request message from the second MIHF. The one or more parameters included within the discovery response message indicates the specific technologies for which the first MIHF supports a MMB handover. The one or more parameters may include a list of the technologies for which a make-before-break (MMB) handover is supported. For example, a parameter may use a specific bit structure wherein each bit is a Boolean representation of whether MMB handover is supported for a specific type of technology.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. provisional application No.60/888,789 filed on Feb. 8, 2007, which is incorporated by reference asif fully set forth.

BACKGROUND

The IEEE 802.21 standard includes mechanisms and procedures that aid inthe execution and management of inter-system handovers. In particular,IEEE 802.21 defines a media independent handover (MIH) function (MIHF)which resides in communications entities of several wireless systemscapable of supporting inter-system handover. For example, FIG. 1 showsan example of network architecture for wireless systems capable ofsupporting inter-system handover. These underlying technologies mayinclude for example 3GPP, 3GPP2 and IEEE-based networks such as IEEE802.xx, code division multiple access (CDMA) 2000; universal mobiletelephone system (UMTS), GSM, long term evolution (LTE) or any otherwireless communication system including future wireless communicationsystems not yet developed.

MIH functions can be implemented in any wireless communication system.The prior art has suggested enhancements regarding the use of severalmessages, including an MIH Capability_Discover Request/Confirm message.Such enhancements include modifications to message parameters so thatMIH capable nodes can discover the capabilities of other MIH enabledpeers in an efficient manner.

The modifications to the message parameters enables a singleMIH_Capability_Discover message to be used to discover all the importantcapabilities of a peer node, such as the number and type of supportedlinks and the link events pertaining to specific link types as opposedto the previous method where one such message had to be sent for everylink type that is supported at a remote end.

Although proposed structures may provide an efficient way of discoveringlink-related capabilities and the type of transport supported, suchstructures do not facilitate determination of other important thecapabilities of these links. Accordingly, a vast improvement in thecapability discovery is still greatly needed.

SUMMARY

A first MIHF receives a MIH capabilities discovery request from a secondMIHF and generates a MIH capabilities discovery response message,including one or more parameters. Then the first MIHF then sends the MIHcapabilities discovery response to the second MIHF. Based on theinformation contained in the MIH capabilities discovery response, thefirst MIHF may receive a handover request message from the second MIHF.

The one or more parameters included within the discovery responsemessage indicates the specific technologies for which the first MIHFsupports a MMB handover. The one or more parameters may include a listof the technologies for which a make-before-break (MMB) handover issupported. For example, a parameter may use a specific bit structurewherein each bit is a Boolean representation of whether MMB handover issupported for a specific type of technology.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 an example of a wireless communication system configured tosupport intersystem handover;

FIG. 2 is a block diagram of a typical wireless communication system;

FIG. 3 is a flow chart of an method of discovering MIH capabilities; and

FIG. 4 is a flow chart of a method of providing MIH capabilities.

DETAILED DESCRIPTION

When referred to hereafter, the terminology “wireless transmit/receiveunit (WTRU)” includes but is not limited to a user equipment (UE), amobile station (STA), a mobile node (MN), a fixed or mobile subscriberunit, a pager, a cellular telephone, a personal digital assistant (PDA),an MIH function, a computer, or any other type of user device capable ofoperating in a wireless environment. When referred to hereafter, theterminology “access point (AP)” includes but is not limited to a Node-B,a site controller, base station, a point of attachment (PoA), a point ofservice (PoS), an MIH function, or any other type of interfacing devicecapable of operating in a wireless environment.

FIG. 2 is a block diagram of a wireless communication system 200 includea wireless transmit receive unit 205 and an AP 1210. The WTRU 205 andthe AP 210 communicate via a wireless communication link, 212.

As shown in FIG. 2, the WTRU 215 includes an MIHF 215, a processor 220,at least one transceiver (225 a, 225 b). The processor 220 is attachedto the MIHF 215 and each of the transceivers 225 a, 225 b. The MIHF 215is configured to carry out media independent handover related processes,including generating an MIH capabilities discovery request, andprocessing an MIH capabilities response.

Also shown in FIG. 2, the AP 210 includes an MIHF 230, a processor 235,at least one transceiver (240 a, 240 b). The processor 235 is attachedto the MIH function 215 and each of the transceivers 225 a, 225 b. TheMIHF 230 is configured to carry out media independent handover relatedprocesses, including processing an MIH capabilities discovery request,and generating an MIH capabilities response. Optionally, the MIHF 230may be located outside of the AP 210 in the network (not shown). Forexample, the AP 210 may be connected to an access router (not shown)which may house the MIHF 230.

FIG. 3 shows a flow diagram of a method 300 for receiving MIHcapabilities. First, the first MIHF sends an MIH capabilities discoveryrequest to a second MIHF, at 310. For the purposes of the method of 300,the first MIHF could be located in an the AP 210 as MIHF 230, or thefirst MIHF could be located in the WTRU 205 as MIHF 215. In a thirdalternative the MIHF could be located in the network (not shown). Inresponse, the first MIHF receives an MIH capabilities discovery responsefrom the second MIHF, at 320. Then the first MIHF makes a decisionwhether to handover to the second MIHF based on information contained inthe MIH capabilities discovery response, at 340.

The MIH capabilities discovery response message includes at least a Lincparameter and an MMB handover support parameter (MMBHandoverSupport).The Linc element will include a list of the network types supported bythe MIHF. The MMBHandoverSupport parameter provides a list of thetechnologies for which an MMB handover is supported. For example, theMMBHandoverSupport parameter may use a specific bit structure whereineach bit is a Boolean representation of whether MMB handover issupported for a specific type of technology. It should also be noted,that it is assumed that all available links support break-before-make(BBM) handover by default, therefore there information relating to BBMhandover capabilities is not needed.

Table 1 shows an example of a possible bit structure for theMMBHandoverSupport parameter; however, one of skill in the art wouldrecognize that many other structures are possible and Table 1 is in noway intended to limit the scope of the invention to the specific bitstructure therein.

TABLE 1 example of possible bit structure for the proposedMBBHandoverSupport parameter Parameter Description MBBHandoverSupport Abit field that has as many bits as there are potential supported lincs.There should be as many entries for this field as there are possiblesupported links. Bit #0-indicates if a MBB handover to 802.3 issupported Bit #1-indicates if a MBB handover to 802.11 is supported Bit#2-indicates if a MBB handover to 802.16 is supported Bit #3-indicatesif a MBB handover to CDMA2000 is supported Bit #4-indicates if a MBBhandover to UMTS is supported Bit #5-indicates if a MBB handover toCDMA2000-HRPD is supported Bit #6-indicates if a MBB handover to GSM issupported Bit #7 to Bit #15-reserved for future use

Optionally, the MIH discovery response message may also include a numberof supported links parameter NumberOfSupportedLinks. This parameterwould indicate the number of links that the communication entityassociated with the MIHF supports. Table 2 shows an example of adefinition for the NumberOfSupportedLinks parameter; however, one ofskill in the art would recognize that many other structures are possibleand Table 2 is in no way intended to limit the scope of the invention tothe specific bit definition or bit structure therein.

TABLE 2 example of the proposed NumberOfSupportedLinks parameter.Parameter Description NumberOfSupportedLinks An 8-bit unsigned integerthat represents the number of supported links in an MIH capable node

FIG. 4 shows a flow diagram of a method 400 for providing MIHcapabilities to a first MIHF. For the purposes of the method of 400, thefirst MIHF could be located in an the AP 210 as MIHF 230, or the firstMIHF could be located in the WTRU 205 as MIHF 215. In a thirdalternative the MIHF could be located in the network (not shown). First,the second MIHF receives an MIH capabilities discovery request from thefirst MIHF, at 410. Next, the second MIHF generates an MIH capabilitiesdiscovery response message, including an MMBhandoverSupport parameterindicating the specific technologies for which the second MIHF supportsan MMB handover, at 420. Then the second MIHF sends the MIH capabilitiesdiscovery response to the first MIHF, at step 430. Optionally, thesecond MIHF may send the MIH capabilities discovery response viabroadcast, multicast or unicast. Based on the information contained inthe MIH capabilities discovery response, the second MIHF may receive ahandover request message from the first MIHF, at 440.

In an alternative embodiment, it may not be assumed that all of theavailable links support BBM handover. In this situation, a thirdparameter may be included in the MIH capabilities discover message toindicate the availability of BBM handover for specific technologies(BBMHandoverSupport). Table 4 shows an example of a possible bitstructure for the BBMHandoverSupport parameter; however, one of skill inthe art would recognize that many other structures are possible andTable 1 is in no way intended to limit the scope of the invention to thespecific bit structure therein.

TABLE 3 Example for the proposed BBMHandoverSupport parameter ParameterDescription BBMHandoverSupport A bit field that has as many bits asthere are potential supported links. There should be as many entries forthis field as there are possible supported links. Bit #0-indicates if aBBM handover to 802.3 is supported Bit #1-indicates if a BBM handover to802.11 is supported Bit #2-indicates if a BBM handover to 802.16 issupported Bit #3-indicates if a BBM handover to CDMA2000 is supportedBit #4-indicates if a BBM handover to UMTS is supported Bit #5-indicatesif a BBM handover to CDMA2000-HRPD is supported Bit #6-indicates if aBBM handover to GSM is supported Bit #7 to Bit #15-reserved for futureuse

The procedures 300, 400, of FIGS. 3 and 4 the first and second MIHFs maybe located in a WTRU 205, an AP 210, or some other network entity suchas an access router (not shown). Optionally, the procedures 300, 400, ofFIGS. 3 and 4 may be performed so that the AP may request the MIHcapabilities of the WTRU 205, and the WTRU 205 may generate and send anMIH capabilities response message to the AP 210 with informationrelating to the MIH capabilities of the WTRU 205.

Although features and elements are described above in particularcombinations, each feature or element can be used alone without theother features and elements or in various combinations with or withoutother features and elements. The methods or flow charts provided hereinmay be implemented in a computer program, software, or firmwareincorporated in a computer-readable storage medium for execution by ageneral purpose computer or a processor. Examples of computer-readablestorage mediums include a read only memory (ROM), a random access memory(RAM), a register, cache memory, semiconductor memory devices, magneticmedia such as internal hard disks and removable disks, magneto-opticalmedia, and optical media such as CD-ROM disks, and digital versatiledisks (DVDs).

Suitable processors include, by way of example, a general purposeprocessor, a special purpose processor, a conventional processor, adigital signal processor (DSP), a plurality of microprocessors, one ormore microprocessors in association with a DSP core, a controller, amicrocontroller, Application Specific Integrated Circuits (ASICs), FieldProgrammable Gate Arrays (FPGAs) circuits, any other type of integratedcircuit (IC), and/or a state machine.

A processor in association with software may be used to implement aradio frequency transceiver for use in a wireless transmit receive unit(WTRU), user equipment (UE), terminal, base station, radio networkcontroller (RNC), or any host computer. The FIRST MIHF may be used inconjunction with modules, implemented in hardware and/or software, suchas a camera, a video camera module, a videophone, a speakerphone, avibration device, a speaker, a microphone, a television transceiver, ahands free headset, a keyboard, a Bluetooth® module, a frequencymodulated (FM) radio unit, a liquid crystal display (LCD) display unit,an organic light-emitting diode (OLED) display unit, a digital musicplayer, a media player, a video game player module, an Internet browser,and/or any wireless local area network (WLAN) or Ultra Wide Band (UWB)module.

1. A method of receiving media independent handover (MIH) capabilities,the method comprising: sending a MIH capabilities request to an accesspoint (AP); receiving a MIH capabilities response, including amake-before-break (MMB) handover parameter.
 2. The method of claim 1wherein the MMB handover parameter includes a list of the technologiesfor which an MMB handover is supported.
 3. The method of claim 1 whereinMMB handover parameter is a Boolean representation of whether MMBhandover is supported for a specific type of technology.
 4. The methodof claim 1 further comprising: determining whether to handover based onthe MIH capabilities response.
 5. A method of providing mediaindependent handover (MIH) capabilities, the method comprising:receiving a MIH capabilities request from a wireless transmit receiveunit (WTRU); sending a MIH capabilities response, including amake-before-break (MMB) handover parameter.
 6. The method of claim 5wherein the MMB handover parameter includes a list of the technologiesfor which an MMB handover is supported.
 7. The method of claim 5 whereinMMB handover parameter is a Boolean representation of whether MMBhandover is supported for a specific type of technology.
 8. The methodof claim 5 further comprising: determining whether to handover based onthe MIH capabilities response.
 9. A media independent handover (MIH)capable wireless transmit/receive unit (WTRU) configured to send andreceive MIH capabilities, the WTRU comprising: a MIH function,configured to generate a MIH capabilities request; a transmitterconfigured to transmit the MIH capabilities request to an access point(AP); and a receiver configured to receive an MIH capabilities response,including a make-before-break (MMB) handover parameter, and to providethe MMB handover parameter to the MIH function.
 10. The WTRU of claim 9wherein the MMB handover parameter includes a list of the technologiesfor which a MMB handover is supported.
 11. The WTRU of claim 9 whereinMMB handover parameter is a Boolean representation of whether MMBhandover is supported for a specific type of technology.
 12. The WTRU ofclaim 9 further comprising: a processor configured to determine whetherto handover based on the MIH capabilities response.
 13. A mediaindependent handover (MIH) capable access point (AP) configured to sendand receive MIH capabilities, the AP comprising: a receiver, configuredto receive a MIH capabilities request from a WTRU; a MIH functionconfigured to generate an MIH capabilities response; and a transmitterconfigured to transmit an MIH capabilities response, including amake-before-break (MMB) handover parameter, and to provide the MMBhandover parameter to the MIH function.
 14. The AP of claim 13 whereinthe MMB handover parameter includes a list of the technologies for whicha MMB handover is supported.
 15. The AP of claim 13 wherein MMB handoverparameter is a Boolean representation of whether MMB handover issupported for a specific type of technology.
 16. The AP of claim 13wherein the receiver is further configured to receive a request tohandover in response to the transmitter transmitting the MIHcapabilities response.